[CentOS-virt] profiling KVM i/o on CentOS 5

Thu Aug 18 16:52:50 UTC 2011
Nick <oinksocket at letterboxes.org>


I am wondering what tools are available to troubleshoot KVM I/O problems on
CentOS 5, given that the kernel is 2.6.18 with some backports to support

 kvm_stat / kvmtrace - These seem to be available in the kvm-tools package.

 ftrace related things seem not to be available.

 OProfile is available, can it be used?

 Also, SystemTap is available, can it be used?

Anything else?

I don't currently have any experience using any of those, except for a brief
experiment with OProfile, but my impression is that it's more of an
event-counting tool - I'm not sure it can time function call execution times.

Which makes me think SystemTap is better suited.  However, this reference [1]
makes me wonder if it can only be used with QEMU/KVM CentOS 6.

Has anyone any experience or prior art they can share or reference, specifically
with profiling virtio_blk?



> BZ#632722 - This update introduces support for tracing of events within QEMU;
> the tracing is similar in its style to DTrace. When used in conjunction with
> SystemTap, it is now possible to trace internal QEMU events such as I/O
> operations and memory allocations